Birds frequently nest in drain gutters, resulting in blockages that can cause flooding and water damage. Bird droppings are also highly acidic and corrode metal and concrete, causing numerous structural problems. Furthermore, where bird nests are located close to electrical cables or installations, their nesting materials can create a serious fire hazard. Birds nesting in chimneys or ventilation systems can also cause air-flow blockages and give rise to potentially serious situations. Last but not least, birds host numerous types of parasites and carry many kinds of infectious diseases.